The present embodiments relate to carrying out and monitoring irradiation of a moving object.
Radiation therapy includes irradiating diseased tissue with x-ray beams, electron beams, or particle beams. Particle therapy is used to treat tissue, such as tumors. Irradiation methods, as deployed in particle therapy, can also be deployed in non-therapeutic areas. For example, irradiation methods may be used in research work (e.g., the irradiation of phantoms or non-living bodies) or the irradiation of materials.
Particles are generated during particle therapy. The particles may be ions, such as protons, carbon ions, or other types of ions. The particles are accelerated to high energies in an accelerator, formed into a particle beam, and then directed onto the tissue to be irradiated. The particles penetrate into the tissue to be irradiated and discharge the particle's energy in a circumscribed region. The depth of penetration of the particle beam into the tissue is a function of the energy of the particle beam. The greater the energy of the particle beam, the deeper the particles penetrate into the tissue to be irradiated.
Movement of the object to be irradiated is taken into account during irradiation. Respiratory movements, for example, can result in a significant change in the position of lung and liver tumors. As a result, the target volume may not be irradiated as desired. During intensity-modulated irradiation, there can be interference effects between the irradation and the target volume movement. Accordingly, a scheduled dosed application to the target volume is impeded.
Different methods are known for controlling the irradiation profile with moving target volumes. For example, gating includes directly or indirectly capturing the movement of the target volume. Irradiation of the target volume then only takes place when the target volume is in a desired location. Tracking may include tracking of the particle beam.
The movement of the target volume can be captured using different methods, for example, using external markers on the patient, by observing the surface of the patient, or using belts or spirometers that capture the respiratory movement. Another option is to continuously record x-ray images or fluoroscopy images of the object. This allows the movement of the object to be captured internally. Possible errors due to differences between external and internal movement can be avoided.
U.S. Pat. No. 7,245,698 B2 discloses a system for irradiating with x-ray beams. The system reconstructs digital tomosynthesis recordings of the object.